Astragalus does appear to lower blood pressure, though the evidence comes primarily from studies where it was used alongside conventional blood pressure medications rather than as a standalone treatment. In clinical trials involving people with kidney disease, adding astragalus to standard treatment reduced systolic blood pressure (the top number) by roughly 10 to 17 points and diastolic pressure (the bottom number) by about 4 to 6 points compared to medication alone.
What the Clinical Evidence Shows
The strongest data comes from two pooled analyses of human trials. A Cochrane review examining astragalus in people with chronic kidney disease found that adding it to standard care reduced systolic blood pressure by an average of 16.65 mmHg and diastolic blood pressure by 6.02 mmHg across two studies with 77 participants. A larger meta-analysis published in Frontiers in Medicine, covering 15 studies and 1,483 participants with hypertensive kidney disease, found that injectable astragalus combined with blood pressure medications reduced systolic pressure by 9.5 mmHg and diastolic pressure by about 4.6 mmHg compared to medication alone.
These are meaningful reductions. For context, a 10-point drop in systolic blood pressure is roughly what you’d expect from a single blood pressure medication. However, there’s an important caveat: nearly all of these studies tested astragalus as an add-on to existing treatment, not as a replacement. There is very little evidence showing astragalus lowers blood pressure on its own in otherwise healthy people.
The one human trial that measured blood pressure with oral astragalus (1,050 mg daily) did find a decrease, but participants were also taking two other herbal extracts at the same time, making it impossible to isolate astragalus as the cause.
How Astragalus Affects Blood Vessels
The blood pressure effects trace back to a compound in astragalus called astragaloside IV, which works primarily by increasing nitric oxide production in blood vessels. Nitric oxide is a molecule your body naturally makes to relax and widen arteries. When blood vessels relax, blood flows more easily and pressure drops.
Specifically, astragaloside IV prevents a process called “uncoupling” in the enzyme that produces nitric oxide. When this enzyme malfunctions, it stops making nitric oxide and starts generating harmful oxidative molecules instead. Astragaloside IV keeps the enzyme working properly, boosting nitric oxide while reducing oxidative stress. It also activates a signaling pathway (PI3K/Akt/eNOS) that further ramps up nitric oxide output. The end result is improved blood vessel relaxation, which directly translates to lower blood pressure.
Beyond blood vessels, astragaloside IV may also influence the hormonal system that regulates blood pressure. Research shows it can reduce levels of angiotensin-II and aldosterone, two hormones that raise blood pressure by tightening blood vessels and causing your body to retain sodium and water. This is the same system targeted by common prescription blood pressure medications like ACE inhibitors.
How Long It Takes to Work
The clinical studies that measured blood pressure ran for three weeks to two months. One study using a 21-day treatment period and another using a two-month period both found significant reductions. This suggests that if astragalus is going to affect your blood pressure, you’d likely see changes within a few weeks to a couple of months, not overnight.
Forms and Dosing
Astragalus comes in several forms: dried root powder, liquid extracts, capsules, and in traditional Chinese medicine, injectable preparations. The injectable form (called Huangqi injection) is what most clinical trials used, which limits how directly those results apply to oral supplements you’d find at a health food store.
The root contains several active components. Astragalus polysaccharides are the most abundant and have broad effects on metabolism, including lowering blood lipids like triglycerides and cholesterol. The saponins, particularly astragaloside IV, are the compounds most closely linked to cardiovascular and blood pressure benefits. Standardized extracts that specify the astragaloside IV content are more likely to deliver consistent doses of the active compound, though head-to-head comparisons between extract types in humans are lacking.
Oral doses in studies have generally ranged widely. The NIH notes that doses up to 60 grams per day for up to four months have not caused apparent adverse effects, though a thorough safety evaluation hasn’t been completed.
Side Effects and Safety Concerns
Astragalus is generally well tolerated in the short term. The National Center for Complementary and Integrative Health reports that oral doses up to 60 grams daily for four months don’t appear to cause adverse effects, though long-term safety data is limited.
The most significant safety concern for people interested in blood pressure effects is the risk of interaction with existing medications. Astragalus can lower blood pressure too much when combined with prescription antihypertensives. It may also amplify the effects of diuretics, potentially causing excessive fluid loss. If you already take blood pressure medication, this combination could push your pressure dangerously low without medical supervision.
People with autoimmune conditions like lupus, rheumatoid arthritis, or multiple sclerosis should avoid astragalus entirely, as it can stimulate immune activity and worsen symptoms. It may also interact with immunosuppressant drugs, anticoagulants, lithium, and hormonal treatments. Animal research suggests it can be toxic to a developing fetus, so it’s not considered safe during pregnancy.
The Kidney Connection
Most of the human blood pressure data comes specifically from people with hypertensive kidney disease, which is worth noting. When high blood pressure damages the kidneys, it creates a cycle: damaged kidneys struggle to regulate fluid and hormones, which pushes blood pressure higher. Astragalus appears to interrupt this cycle on multiple fronts. Beyond lowering pressure directly, the meta-analysis of 15 studies found it improved kidney function markers when added to standard treatment.
This doesn’t mean astragalus only works for people with kidney problems, but it does mean the strongest evidence applies to that population. Whether the same magnitude of blood pressure reduction occurs in people with simple high blood pressure and healthy kidneys remains unclear.